DESCRIPTION: Exaggerated vasoconstrictive mediated blood pressure (BP) response to stress (i.e., reactivity) has been hypothesized as contributing to the higher prevalence of essential hypertension (EH) in blacks compared to whites in the United States. Although EH has its pathobiologic origins in childhood, little longitudinal reactivity research has been conducted in youth, especially comparing ethnic differences from childhood through early adulthood. Continued longitudinal studies of the investigators' BP STRESS cohort (a biracial sample of 304 youth with positive family histories of EH who will be 13 to 20-years old) for an additional 5 years will provide a better understanding of the relationships between cardiovascular (CV) reactivity in youth and the pathogenesis of EH. Particularly informative will be evaluation of vascular endothelial function (i.e., plasma endothelin-1 [ET-1] and endothelium dependent arterial dilation [EDAD]), which has been shown to play a major role in vasoconstrictive mediated BP control and may be an important mechanistic pathway linking CV reactivity to EH. The specific aims are to determine: 1) whether BP reactivity during childhood predicts changes in preclinical markers of EH risk including resting BP, left ventricular geometry, EDAD and ET-1 up to 11 years later after controlling for expected predictors (e.g., sex, ethnicity, age, resting BP, ambulatory BP, adiposity; 2) influences of ethnicity, sex and a select group of moderator variables (e.g., environmental stress, stress coping styles, aerobic fitness) on CV reactivity from childhood to early adulthood; and 3) stability of CV reactivity, 24-hour ambulatory BP, and ET-1 from childhood to early adulthood. Long term objectives are to provide an understanding of the development of children's CV reactivity and its influence upon preclinical markers of EH. Some subjects will develop EH which will also permit prediction of overt disease. This information may help identify youth at greatest risk for development of EH and facilitate development of interventions that may prevent early onset of EH.